Low concentrations of muscarine potentiate M-current in bullfrog sympathetic B-neurones.
The concentration-dependence of the effect of muscarine on M-current (IM) and the underlying M-conductance (gM) in B-cells of bullfrog sympathetic ganglion was examined using whole-cell recording techniques. High concentrations of muscarine (> or = 200 nM) produced the classical suppression and over-recovery of steady-state IM at -30 mV. By contrast, low concentrations of muscarine (< or = 30 nM) shifted the gM activation curve to more negative potentials, increased the activation time constant (tau a) and increased steady-state IM. This effect may reflect muscarine-induced changes in submembrane Ca2+ concentration.
Kurennyi
D E
DE
Department of Pharmacology, University of Alberta, Edmonton, Canada.
Chen
H
H
Smith
P A
PA
D000320:Adrenergic Fibers / Q000187:drug effects*; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009116:Muscarine / Q000494:pharmacology*; D018721:Muscarinic Agonists / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D011892:Rana catesbeiana; D011976:Receptors, Muscarinic / Q000187:drug effects*
D015220:Calcium Channels; D018721:Muscarinic Agonists; D011976:Receptors, Muscarinic; D009116:Muscarine